Ported from https://en.wikipedia.org/wiki/LEB128#JavaScript_code

LEB128.cs

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    public static void Main()
    {
        var encoded = LEB128.EncodeSignedLeb128FromInt32(624485);
        var str = string.Concat(encoded.Select(entry => entry.ToString("X")));
        Console.WriteLine(str);
        var result = LEB128.DecodeSignedLeb128(encoded);
        Console.WriteLine(result);
    }
}

class LEB128
{
    public static byte[] EncodeSignedLeb128FromInt32(long value)
    {
      var result = new List<byte>();
      while (true) {
        var b = value & 0x7f;
        value >>= 7;
        if ((value == 0 && (b & 0x40) == 0) || (value == -1 && (b & 0x40) != 0))
        {
          result.Add((byte)b);
          return result.ToArray();
        }

        result.Add((byte)(b | 0x80));
      }
    }

    public static long DecodeSignedLeb128(byte[] input)
    {
      var result = 0;
      var shift = 0;
      foreach (var b in input)
      {
        result |= (b & 0x7f) << shift;
        shift += 7;
        if ((0x80 & b) == 0)
        {
          if (shift < 32 && (b & 0x40) != 0)
          {
              return result | (~0 << shift);
          }

          break;
        }
      }

      return result;
    }
}

Description

Encode and decode LEB128 (according to what Wikipedia says) in C#.

Try it online.

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Output

E58E26
624485